Such a conclusion, however, as we have also seen, only holds good within those normal limits which an attempt has here been made to determine. The phenomena we have been considering are strictly normal phenomena, having their basis in the conditions of tumescence and detumescence in animal and primitive human courtship. At one point, however, when discussing the phenomena of the love-bite, I referred to the facts which indicate how this purely normal manifestation yet insensibly passes over into the region of the morbid. It is an instance that enables us to realize how even the most terrible and repugnant sexual perversions are still demonstrably linked on to phenomena that are fundamentally normal. The love-bite may be said to give us the key to that perverse impulse which has been commonly called sadism.
There is some difference of opinion as to how "sadism" may be best defined. Perhaps the simplest and most usual definition is that of Krafft-Ebing, as sexual emotion associated with the wish to inflict pain and use violence, or, as he elsewhere expresses it, "the impulse to cruel and violent treatment of the opposite sex, and the coloring of the idea of such acts with lustful feeling."[83] A more complete definition is that of Moll, who describes sadism as a condition in which "the sexual impulse consists in the tendency to strike, ill-use, and humiliate the beloved person."[84] This definition has the advantage of bringing in the element of moral pain. A further extension is made in Féré's definition as "the need of association of violence and cruelty with sexual enjoyment, such violence or cruelty not being necessarily exerted by the person himself who seeks sexual pleasure in this association."[85] Garnier's definition, while comprising all these points, further allows for the fact that a certain degree of sadism may be regarded as normal. "Pathological sadism," he states, "is an impulsive and obsessing sexual perversion characterized by a close connection between suffering inflicted or mentally represented and the sexual orgasm, without this necessary and sufficing condition frigidity usually remaining absolute."[86] It must be added that these definitions are very incomplete if by "sadism" we are to understand the special sexual perversions which are displayed in De Sade's novels. Iwan Bloch ("Eugen Dühren"), in the course of his book on De Sade, has attempted a definition strictly on this basis, and, as will be seen, it is necessary to make it very elaborate: "A connection, whether intentionally sought or offered by chance, of sexual excitement and sexual enjoyment with the real or only symbolic (ideal, illusionary) appearance of frightful and shocking events, destructive occurrences and practices, which threaten or destroy the life, health, and property of man and other living creatures, and threaten and interrupt the continuity of inanimate objects, whereby the person who from such occurrences obtains sexual enjoyment may either himself be the direct cause, or cause them to take place by means of other persons, or merely be the spectator, or, finally, be, voluntarily or involuntarily, the object against which these processes are directed."[87] This definition of sadism as found in De Sade's works is thus, more especially by its final clause, a very much wider conception than the usual definition.